How to avoid fights with my cousins?

Just act stupid and funny until they laugh instead of getting mad. For example when you fight with your girl cousin tell her, "You know I still love, do you love me?" If she looks at you with a serious face, then tell her, "If I make you laugh that means you love me to, ready? On the count of three, 1, 2 3. While looking at her with a straight face. And at the end you start cracking a smile until she laughs. Then you all laugh cause it is so retarded.